Lead author Dr. Heather Patisaul of North Carolina State University and colleagues at Duke University said Firemaster 550 is used in polyurethane foam in a wide variety of products, ranging from mattresses to infant nursing pillows.

It was developed to replace a class of fire retardants being phased out because of concerns regarding health effects.

The study involved pregnant lab rats assigned to three groups: a control group that was not exposed to Firemaster 550, a low-dose group that ingested 100 micrograms of Firemaster 550 once per day throughout pregnancy and nursing, and a high-dose group that ingested 1,000 micrograms on the same schedule.

These environmentally relevant doses were lower than the doses used in industry-funded studies.

The high-dose mothers had much higher thyroid hormone levels than the control group, while low-dose mothers had marginally higher thyroid hormone levels, the study said.

Researchers also found extremely rapid weight gain in the offspring -- high-dose male pups were 60 percent heavier than the control group, while high-dose female pups were 31 percent heavier than the control group.

The increased weight in female pups contributed to the early onset of puberty. In addition, high-dose female pups also had difficulty regulating their glucose levels as adults. High-dose males had thickened walls in the left ventricle of the heart, suggestive of cardiovascular disease, the study said.

The findings were published online in the Journal of Biochemical and Molecular Toxicology.

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